There are presently in use in connection with the construction of printed circuit boards various soldering systems. One of the major soldering processes is the Hot Air Solder Leveling process known as the HASL process. Solder machines using the process are sold by various companies, e.g., Teledyne and Cemco. As the solder is used in such HASL process, it becomes contaminated with copper impurities and it is no longer useful and thus must be replenished.
In certain cases, the copper laden solder is sent to a reclaimer for removal of the impurity and new solder is used. This requires personnel time to physically replace the solder and also results in equipment down time. This is clearly not a cost effective way of handling the situation because of the expense of the new solder in comparison to what is paid by the recycler to the company.
Other methods have been proposed for use in removing copper from the solder. See U.S. Pat. No. 5,388,756 which discloses a continuous system. Also note the Japanese Patent No. 1-168826 described in this U.S. Pat. No. 5,388,756. In general, the way the continuous system operates as disclosed in U.S. Pat. No. 5,388,756, copper removal is not as great as is desirable and results in more new solder having to be added at greater cost to replenish the solder in the HASL machine.
Another system operating on a non-continuous basis has been proposed and has been sold in the USA. The system was designed by the AEA (a UK government agency) and utilizes two skimming tanks and an exterior heated linking pipe connected to the HASL machine.
This system attempts to control flow to the skimming operation in two tanks so that cleaned solder can be made available to the HASL system. However, this system has resulted in difficulties in maintenance as well as less than desirable flow of spent solder through the linking pipe thereof, i.e., the pipe connected between the HASL machine and the tanks. Because of the nature of the construction of the linking pipe and external heating system therefore and the inability to keep the solder at about 500.degree. F. throughout the linking pipe as constructed, solidification of the solder has sometimes developed in the linking pipe with resultant incomplete transfer of copper contaminated solder.
Accordingly a new and improved system was needed to efficiently and more cost effectively remove copper contaminants from solder.
Additionally, a new and improved system was required that could be tested in the field without interfering with HASL operation. Further a new and improved linking pipe was needed which would be able to maintain solder flow between the HASL and the copper decontamination system. The present invention provides a system which meets the requirements listed above.